A typical communications network includes a lot of different types of network devices. For example, a typical communications network may include host devices, which act as the source or destination of a particular flow of traffic, routers and/or switches, which act to forward traffic flows toward their appropriate destinations, and security devices, which provide, for example, firewall or other security functionality. These different types of network devices may be interconnected via links.
In some instances, a link between a pair of network devices may fail or a network device may fail. In those instances, it is important that the communications network be able to continue to route traffic. Therefore, some networks include redundancy. For example, a second network device may act as a backup for a first network device. If any part of the first network device fails, the entire first network device may fail over to the second network device.